1. Field of the Invention
The present invention relates to load lifting devices generally and, more particularly, but not by way of limitation, to a novel column for load lifting devices.
2. Background Art
Many load lifting devices, such as free standing vehicle lifts, for example, require vertical support members within, or upon, which a moving member rides.
Typically, such columns are formed of heavy steel stock of a single wall thickness, often fabricated by expensive roll forming. Thicknesses may range up to 3/8-inch or more. Such a construction "wastes" material in the sense that some portions of the column are thicker than the loads thereon require and the resulting columns are heavy in relation to the loads that they can handle.
Many manufacturers of such columns wish to provide a series of such columns with each column in the series sized to handle a given maximum load. Typically, each column in the series has its own design and it is not possible to make small adjustments to a basic design to increase the load handling capabilities thereof, particularly when the elements of the column are produced by the expensive method of roll forming because the roll forming machinery lacks flexibility.
A substantial disadvantage of columns for vehicle lifts having internal movable members is that the internal volume of the columns is almost entirely reserved for the movement therein of the movable members. Consequently, electrical cables, hydraulic lines, pneumatic lines, equalizing cables, and the like must be located on the outside of the column. Such exposed elements present a safety hazard to operators and present a risk of damage to the lift in a busy environment.
A further problem with having the moving member substantially fill the interior volume of the column is that workmen often drill holes through the wall of the column for the attachment thereto of cables, control panels, etc. When the lift is next operated, the moving member is damaged.
Accordingly, it is a principal object of the present invention to provide a column for load lifting devices that is lightweight, yet rigid, and has a high capacity to weight ratio.
It is a further object of the invention to provide such a column to which relatively minor changes can by made to increase the load handling capability thereof.
It is an additional object of the invention to provide such a column in which operating lines and cables can be disposed.
Other objects of the present invention, as well as particular features, elements, and advantages thereof, will be elucidated in, or be apparent from, the following description and the accompanying drawing figures.